1. Field of the Invention
With reference to the classification of art as established in the United States Patent Office this invention is found in the general Class entitled, "Metal Working" (Class 29) and in the subclass thereunder entitled, "Cutters" (subclass 95 R) and also to the class entitled, "Abrading" (Class 51) and to the subclass entitled, "Work Holders -- Gauging Devices" (subclass 220).
2. Description of the Prior Art
Cutting tools and particularly back spot facing tools are well known and particularly that shown in the reference U.S. Pat. No. 3,827,821. In general a back spot facing tool is used in high production and in automatic positioning requiring either manual or hydraulic means for positioning and closing the cutting blade. In the above reference patent an unsymmetrical cutting tool is shown and, as reduced to practice, has proved highly satisfactory particularly with the shorter portions of the blade being about three-quarters of the full blade portion. Whereas the grinding fixture for the grinding of the cutting tool bit, as shown in the above-mentioned patent, anticipates grinding of the tool with only one clamping operation in the tool holder, the fixture as shown in the present apparatus anticipates the difficulty of grinding such a tool and the irregularities that arise in a one holder fixture. In the new cutting bit holder the cutting tool is precisely held for sharpening of only one cutting edge to a precise angle with compensation being made for the upper and forward rake formed on the cutting tool bit.
In an alternate bit and adjacent the cutting edge of each portion of this bit is formed a chip breaker. The holder is adapted for such a chip breaking groove to be ground in the bit and there is provision for a resharpening of the bit.